Tardigrades extracted from Antarctic algae can survive a decade without water, temperatures near absolute zero, and 10 days of exposure to the open vacuum of space in 2007, coiled into a desiccated shell they call a ton until conditions improve.

A tardigrade pulled from a mass of Antarctic algae can lose almost all the water in its body, places its eight legs under a round shell called a ton, and waits. It can wait through a decade of drought. It can wait at temperatures a few degrees above absolute zero, which is colder than anything that occurs naturally on Earth. In 2007, aboard the European Space Agency’s FOTON-M3 capsule, the water bear waited out ten days of open vacuum, unfiltered solar ultraviolet light, and cosmic radiation — then hydrated and produced normal offspring once it returned to Earth.

Most of them lived.

They were the first animals confirmed to survive direct exposure to the vacuum of space. Not protected inside the capsule. Not tucked behind a window. It was displayed on a tray on the outside of a spacecraft in low Earth orbit, where pressure is virtually zero and the temperature on the sunlit side can fluctuate by more than 200 degrees in a single orbit.

What is a toon actually

Tardigrades are microscopic. Most are shorter than a millimeter. They walk on eight stubby, clawed legs, eat by piercing plant and algae cells with a clamp, and have been called water bears by biologists since the 18th century.

They need liquid water to do anything to survive. Feeding, locomotion, reproduction, metabolism – all of this depends on the layer of water around the algae, lichen or sediment in which they live.

When the water goes, so does the tardigrade, but not as everything else goes. He pulls his legs inward. It shrinks its body into a barrel about half its normal length. It expels almost all of its internal water. It enters a state biologists call cryptobiosis, or hidden life, in which its metabolism drops to near zero — measurable only as a whisper in the background.

The peel is the tuna. In this form, the tardigrade is not alive in any active sense. He also didn’t die. It has been temporarily suspended.

Glass trick

What prevents the paused tardigrade from collapsing is a class of molecules called intrinsically disordered proteins, or TDPs. When water leaves the cell, TDPs reorganize themselves into a stable, glass-like matrix that fills the interior. Everything inside – DNA, ribosomes, membranes, enzymes – is held in place, as if suspended in a clear resin.

This process is called vitrification. Molecules cannot move. The chemical reactions that normally lead to the breakdown of proteins slow to a crawl. Ice crystals, which kill normal cells by puncturing membranes as they expand, cannot form because there is almost no water left to freeze.

Add water again and the glass dissolves. Tardigrade spreads its legs. He starts walking, feeding, and looking for something to eat.

2007 experience in detail

The mission flew aboard the European Space Agency’s FOTON-M3 capsule in 2007. The samples came from species collected from European habitats and were dried in tons before launch. Once in orbit, a hatch opened on the outside of the capsule and the trays of dried water bears were exposed for ten days.

Some samples got vacuum only. Some got a vacuum as well as the full spectrum of solar ultraviolet radiation, including the ultraviolet (UV-B) and UV-C wavelengths that the atmosphere normally filters out before it reaches anything on Earth. Some obtained vacuum as well as cosmic ionizing radiation.

The vacuum alone did almost nothing. Survival was almost complete. UV rays were the killer, but even in specimens exposed to the full solar spectrum, a fraction survived, hydrated, and laid viable eggs.

The Tardigrades flew again in 2011 aboard NASA’s space shuttle Endeavour. In 2019, several thousand were spilled on the moon’s surface when Israel’s Beresheet lander broke apart during landing — although microbiologists said they actually had a chance. Moon colonization is actually zero Without liquid water or oxygen. In 2021, live tardigrades ascended to the International Space Station for a long-term genetic study.

“We want to see what tricks they use to survive when they arrive in space, and over time, what tricks their offspring use,” explained the ISS experiment researchers. “Are they the same or do they change over generations? We don’t know what to expect.”

Radiation, new dye

The vacuum trick and the cold trick are impressive. The radiation trick is weird.

Ionizing radiation kills by cutting strands of DNA and producing highly reactive molecules – free radicals – that attack proteins, membranes and genetic material from within. Doses that would kill a human are routinely escaped by tardigrades.

In 2024, a team at the Beijing Institute of Life Sciences led by Lingqiang Zhang published it Paper describing a new species of tardigrade — Hypsibius henanensiscollected from algae in China’s Henan Province — and the genes that were turned on when exposed to radiation. The team found thousands of genes that became more active under stress, and are involved in DNA repair, cell division, hormone metabolism, and the immune response.

One gene stood out. DODA1 allows tardigrades to produce betalains, the same class of red-purple antioxidant pigments that give beets their color. Betalain compounds eliminate reactive chemical radiation generated inside the cell before it can cause any damage. When the team treated human cells with tardigrade betalains and then irradiated them, the treated cells survived much better than untreated cells.

This is the practical class. If a beet red pigment made by an animal that lives in algae can protect human cells from radiation damage, potential applications range from treating cancer to protecting astronauts on a multi-year round trip to Mars.

The temperature range is almost ridiculous

The numbers on the tardigrade’s thermal tolerance are sound and made up so you can check them.

In ton form, they survived brief exposure to intense heat—hot enough to bake bread twice. At the other end, they were cooled to a fraction of absolute zero and then revived. This is colder than any normal surface in the solar system, colder than the shadowed floors of craters on the Moon, and colder than the night side of Pluto.

The trick is the same one that protects them from the void. With almost no water in the cell, the sharp, expanding ice crystals that puncture normal tissue during freezing never form. What’s left is the TDP glass, which holds each delicate structure in place so that warmth and water return.

They were also exposed to pressures of about 6,000 atmospheres — nearly six times the pressure at the bottom of the Mariana Trench — and lived. The space war covered the 127 minutes the Soviet Venera 13 probe spent on the surface of Venus, where pressures reach about 90 atmospheres and temperatures that melt lead. The toon tardigrade will ignore flower pressure. Heat will still cook it, but pressure alone will not.

How long can they wait?

The decade number in the title is a conservative claim, and it comes from Antarctic mosses because that is where some of the longest confirmed revivals have been documented. Water bears pulled from dried algae specimens stored in museums have been rehydrated and revived after long periods of dormancy, including specimens frozen for decades that have come back to life.

There are older claims. Reports dating back to the early 1900s describe revivals of museum moss specimens dating back more than a century, although modern researchers consider these specimens unconfirmed. The contract is secure. Thirty years have been documented. There is still a longer debate in the literature.

What cannot be disputed is that the clock actually stops. A ton at -20 degrees Celsius in a bowl of dry moss on a shelf does not equate to aging in any biological sense. It is simply there, waiting for water.

Where they actually live

Tardigrades are not creatures of extremes. They only do extreme survival tricks when they have to. In ordinary life, they live in the film of water stuck to moss pillows on a stone wall, in lichens on tree bark, in wet leaf litter, in freshwater sediments, in the interstitial spaces of beach sand, in moss beds in Antarctica, in moss beds on suburban roofs.

Squeeze a handful of wet moss from almost anywhere on Earth into a dish of water, wait an hour, then place a drop under a decent microscope. There will be tardigrades. There are more than 1,300 known species. It is one of the most widespread animal groups on the planet.

Their extreme flexibility is not an adaptation to space or to Antarctica specifically. It is an adaptation to the monotonous catastrophe of the pond drying up. A moss pad on a rock in the sun gets wet, dry, wet, dry, wet, dry during the summer. A creature that can stop during dry stretches inherits the moss.

Void tolerance is a side effect. A cell that can protect itself from completely drying out is, incidentally, protected against many of the things that also strip tissues of water, such as freezing, boiling, extreme vacuum, high ultraviolet radiation, and ionizing radiation. Evolution solved the puddle problem, and the solution occurred in orbit.

Why does this still matter?

Understanding TDP glass and betalain pigment is not just a biological curiosity. Freeze-dried vaccines containing TDP-like proteins can allow them to survive during transport without refrigeration. Radioprotective compounds derived from tardigrade genes could protect tissues during cancer radiation therapy or during long-duration manned spaceflight. The 2021 International Space Station experiment has been sent Thousands of tardigrades to learn how their genes behave across generations in microgravitywith a focus on human applications in Mars missions.

There is also the question of deep time. If an algae-dwelling animal on Earth can survive in open vacuum and cosmic radiation for ten days as a dry husk, then the panspermia argument—the idea that life, or at least its raw ingredients, can travel between worlds inside meteorites—comes one step closer to plausibility. Not proven. It’s just hard to refuse.

Of course, you wouldn’t wake up a tardigrade in a tunnel on a piece of rock that was blasted out of the ground by an ancient collision, on Mars. There is no liquid water on Mars. But the moral of the 2007 experience is that the crossing itself is survivable. The vacuum, cold and radiation of interplanetary space alone do not kill the passenger.

The crust is on the shelf

Somewhere now, on the underside of a piece of Antarctic algae preserved in a jar in a laboratory in Copenhagen, Tokyo or Cambridge, there is a barrel of an object about a quarter of a millimeter long. He does not have a measurable heartbeat because he does not have a heart. It has no measurable metabolism because it contains no water. Its DNA is held in place by a glassy matrix of disordered proteins made by the animal in the final minutes before it dries out.

Drop it in a puddle. Wait half an hour. It will spread its eight legs, open its snout, extend its style, and begin searching for algae to eat, as if nothing had happened.

Which, from his point of view, is absolutely correct. He did nothing.